The trio shares Hispanic heritage, but each thought of him- or
herself differently:

Chavez considered herself of mixed European heritage. She had
roots in Spain's New World colonies going all the way
back to the 1590s, when an ancestor sailed to Mexico. In a
surprise discovery, she learned many of her family were "conversos,"
Jews forced to convert to Catholicism, many of whom continued to
practice Judaism in private. A large number of conversos left Spain during
the Inquisition.
Her grandmother's custom of turning a religious statue to face
the wall hinted at the surprise—you
can read more about this custom in Chavez' essay here.

Grenier, who'd always identified with American Indian roots
because of a story in his mother's family, discovered he had a
conquistador ancestor in Don
Juan de Oñate
's army (kind of the opposite of having American Indian roots).

Grenier seemed shaken when his connection to American Indian
heritage was in question, but Gates' team did find a 1663
record at the New
Mexico state archives identifying an ancestor as "Indio."
So he does have American Indian roots, just further back
than he'd believed. I wonder if he'll still identify
himself as being American Indian?

Rodriguez is Puerto Rican through her father and Dominican
through her mother. Gates described her tree as a "tangled web," provoking a hilarious reaction from Rodriguez.
Her father's family intermarried repeatedly, likely in an effort
to preserve "pure" bloodlines. Three of her
third-great-grandfathers were brothers, and her
great-grandparents were first cousins.

Her surprise came on a
trip to the Dominican Republic to learn more about her mom's
family from a great-aunt. The aunt's parents—Rodriguez's
great-grandparents—weren't married, it turns out. Her
great-grandfather had a legal wife, and the two women raised the
children together.

Also as before, Gates emphasized that mixing between ancestral
groups or "races"—in this case, colonial Spanish and American
Indian peoples—was common. This is part of what makes the
definition of American really pretty broad.